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## Rivet analyses reference

### ALEPH_1997_I427131

$\pi^0$ spectrum at LEP1
Experiment: ALEPH (LEP)
Inspire ID: 427131
Status: VALIDATED
Authors:
• Peter Richardson
References:
• Z.Phys. C74 (1997) 451-461
Beams: e- e+
Beam energies: ANY
Run details:
• e+e- -> hadrons at Z pole

Measurement of the $\pi^0$ spectrum, and distribution of $p_T^{\text{in}}$ and $p_T^{\text{out}}$ with respect to the sphericity axis by the ALEPH experiment at LEP1.

Source code: ALEPH_1997_I427131.cc
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/Sphericity.hh" #include "Rivet/Projections/FinalState.hh" #include "Rivet/Projections/UnstableParticles.hh" #include "Rivet/Projections/Beam.hh" namespace Rivet { /// @brief pi0 spectrum class ALEPH_1997_I427131 : public Analysis { public: /// Constructor DEFAULT_RIVET_ANALYSIS_CTOR(ALEPH_1997_I427131); /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { // // Initialise and register projections declare(Beam(), "Beams"); const FinalState fs; declare(fs, "FS"); declare(Sphericity(fs), "Sphericity"); declare(UnstableParticles(), "UFS"); // Book histograms book(_h_x , 2, 1, 2); book(_h_in , 4, 1, 1); book(_h_out, 3, 1, 1); } /// Perform the per-event analysis void analyze(const Event& event) { const FinalState& fs = apply(event, "FS"); if (fs.particles().size() < 2) { MSG_DEBUG("Failed ncharged cut"); vetoEvent; } MSG_DEBUG("Passed ncharged cut"); const Sphericity& sphericity = apply(event, "Sphericity"); // Get beams and average beam momentum const ParticlePair& beams = apply(event, "Beams").beams(); const double meanBeamMom = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0; MSG_DEBUG("Avg beam momentum = " << meanBeamMom); for (const Particle& p : apply(event, "UFS").particles(Cuts::pid==111) ) { const Vector3 mom3 = p.p3(); const double pTinS = abs(dot(mom3, sphericity.sphericityMajorAxis())); const double pToutS = abs(dot(mom3, sphericity.sphericityMinorAxis())); _h_x ->fill(mom3.mod()/meanBeamMom); _h_in ->fill(pTinS ); _h_out->fill(pToutS ); } } /// Normalise histograms etc., after the run void finalize() { scale(_h_x , 1./sumOfWeights()); scale(_h_in , 1./sumOfWeights()); scale(_h_out, 1./sumOfWeights()); } //@} /// @name Histograms //@{ Histo1DPtr _h_x, _h_in, _h_out; //@} }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(ALEPH_1997_I427131); }